Rectifier alarm system



"re-b. I26, 1929.

' l [,70321'47 w. H. 'r'. HOLDEN gmcTIFIEn ALARM sxsrsu Original Filedlas? 5. 1924 2 Smets-sneer 1 mRNE Y Feb; 26,1929. 1,703,147 w. H. 'r.HOLDEN RECTIFIER ALARM SYSm original Filed nay 5,- '1924 2 sheets-sheetl2 )ATTORNY Patented Feb. 26,1929. UNITED STATES PATENT: oFF-LCE.

WILLIAM H. T. HOIIDEN, OF BROOKLYN, NEW YORK, ASSIGNOR T0 .AMERICANTELEPHONE AND TELEGRAPH COHIPANY, A CORPORATION 0F NEW YORK.

nncrmmn um srsrmc.

l' ltli'lginal application ledilay 5, 1924,

cation Serial No. 711,302, filed May 5, 1924.

In the operation of a system'designed to rectify an alternating voltageso that a unidirectional voltage may .thereby be produced which may beutilized, for example, to charge a storage battery, it is important thatany failure of the rectifying device to properly v rectify the appliedalternating voltage may be instantly known.

Itis the object of this invention to provide a method and means forinstantly indicating any failure of a rectifying device tol properlyrectify the plate voltage.

Other objects of this invention will be apparent from the followingdescription when read in connection with the attached drawing of whichFigure 1 shows the invention in its simplest form; Figs. 2, 3 and 4 showgraphically the principle of operation of the invention; and Figs. 5 and6 show other forms of embodiment of the invention.

I n Fig. 1, a source 1 of alternating voltage is adapted to be connectedby means of Vcertain blades of the single throw triple pole switch 2with the primary winding 3 of the transformer 4. The secondary winding 5of this transformer which includes all of thek turnsbetween theterminals 6 and 7, is effectively connected across the electrodes of therectifying device 9. That portion of the winding 5 designated at 5 isused to furnish the current necessary for heating the cathode 10 of therectifier. The battery 12,

which is to be charged by the unidirectlonal.

current produced by the. rectifying system', is connected between theanode 11 and the terminal 6 of the winding 5. A load `13 is connectedacross the terminals of the battery 12. Connected across the anode andcathode of the rectifier 9 is a marginal relay 14 in series with a.controlling reslstance 15.

This marginal relay, which is preferably of' the slow release type, isintended Vto operate -upon the margin existin between the voltage of thebattery 12 an the average alternating voltage when the device 9 isproperly rectifying. The relay 16, which operates whenever the switch 2is closed and which is deenergized when the said switch is-open, is

` imposed upon the voltage ofthe battery Serial No.r711,802. Divided andthis application led October 9, 1925. serial no. 61,809.

intended to prevent the continuous operation of the alarm device 17 whenthe rectlfier 9 is intentionally stopped from operating. l

The manner in which this circuit operates to carry out the inventionwill be clearly understood from the foregoing description considered inconnection with the diagrams shown in Figs. 2, 3 and 4. Let it beassumed that the switch 2 is closed, so that an alternating voltage willbe applied by the winding 3 to the winding '5. This alternating voltage1s represented in Fig. 2 by A. Since thebattery 12 is in the samecircuit as winding 5, the voltage across winding 5 will be super- 12represented by B of Fig. 2. If there were no rectlfying device connectedwith the circu1ts, the resultant voltage applied to the marginalrelaywould have the form of the dotted wave represented by C of Fig.'2.As

is well known, the superposition of the alternating wave upon the directcurrent voltage results, 1n effect, in ashifting of the zero axis of thealternating wave. Fora symmetrical wave, the line representing theaverage value of successive half waves is, of course, the zero axis ofthe wave and this would coincide with theline representing the directcurrent voltage B. The proper operation of the rectifying device 9 inthe circuit causes unsymmetrical half waves, andthelne represent` ingthe average value of the alternating voltage wave will not coincide withthe line of the direct voltage. This difference of voltage, representedby the separation of the two lines, maintains the marginal rela operatedand thereby prevents the operation of the buzzer 17 by keeping thecircuit of the latter open.

For a clearer understanding of this, consider that during the intervala-b of the voltage wave A, the terminal 8 of the winding 5 is positivewith respect to its terminal 6. With the battery 12 poled as shown inFig. 1, the

lalternating voltage during thisrhalf cycle raam 14. During the halfcycle represented by the interval b-c, the alternating voltage willoppose the direct voltage of the battery 12, but the polarity of theanode 11 will not become positive until the instant b isreached when thealternating voltage exactly equals the direct vltage. During theinterval b c', the anode 1l will' remain' positive with respect to itscathode 10, and in consequence thereof a How of current will take placeacross the gap of the rectifier 9, causing the voltage across theelectrodes to drop substantially to zero. llhis drop in the voltage isrepre? sented by the dot and dash line extending across the trough ofthe wave C between the points t c. At the point c the alternating anddirect voltages again become equal, and thereafter the anode i1 isnegative with respect to its cathode so that further current iiowthrough the tube ceases.

lt the tube 9 is functioning properly, current will new therethroughduring some part of every other half cycle, and during the interval inwhich such current flow takes place the voltage across the electrodeswill drop substantially to zero. As stated heretofore, the voltageacross the circuit including the marginal-relay 14 is the voltage acrossthe electrodes of the rectilier. When the tube is functioning properly,this voltage has the form represented by the wave of F ig. `3, and sincethe half waves are unsyrnmetricall with respect to their zero axis, thatis, the line which coincides with the line representing the directvoltage B, the average value of successive half waves will not berepresented by a line coinciding with the line B, but'will be displacedand may be represented by the line D. The marginal relay 14 is adjustedto be operated at the voltage represented by D and not to operate at thevoltage represented by B. Accordingly, when the rectifier is operatingproperly, this marginal relay remains operated by .virtue of the excessvoltage, and by holding up its armature it maintains open the circuit ofthe buzzer 17. lt should be remembered that, upon the closing of switch2, relay 16 is operated and its armature remains pulled up', so that thefuture control of the circuit of the buzzer 17 resides in the marginalrelay. It the rectifier 9 fails to rectify, viz., current does not nowbetween the electrodes durir the interval c', the voltage across thesee' ectrodes will therefore not drop to zero, as represented by the dotand dash line,but it will be maintained throughout that portion oi thecycle as represented by the dot ted line. Accordingl the successive halfwaves of the curve (l, will be symmetrical with regard to their axis,which, as stated, co-

v incides with the line B, and sincethe half waves are symmetrical, thisline represents i the average value of the successive half cycles.

This means'that the average value of the wave C coincides with thedirect voltage B,

and accordingly thereis no mar 'n of voltage to maintain operated themarginal relayv14`. This relay will accordingl be' released, and itsarmature will fall bac closing the circuit of the buzzer 17 which willindicate to an attendant that the rectifier 9 is not functioningproperly, Upon opening the switch 2 in order to disconnect the source ofalternating voltage from the rectifying system, the

circuit of relay 16 will be opened, which, iny

turnwill open the circuit of the buzzerl'i' and discontinue the givingof the alarm. The function' of relay 16 is to prevent the continuousoperation of\ the buzzer during the time in which the rectifier isurposely not operating. The coincidence o average voltage of the wave Cand of the direct'voltage B is represented in Fig. 4.

The arrangement shown in Fig. 5, in which the same reference charactershave 'been used to designate the same parts as shown'in Fig.

1, differs from that shown in Fi l principallyA in the use of adii'erential re ay in place of the marginal relay shown in Fig.- 1. The

differential relay 14 has one winding 18 connected across the terminalsof the battery 12. Another windin 19, differential with respect to thefirst win ing, is connectedacross the electrodes of the rectifier 9. Theremainder of the circuit is substantially as shown in Fig. 1. Thisarrangement is intended to insure proper operation of the alarm relay incase the battery voltage increased, due toits being charged, and thuscut down the margin between the direct current potential of the batteryand the average alternating voltage of the unsymmetrical wave, i. e.,the 'partly rectiiied wave. By the use oi' a device operating upon thedierential the diiliculty arising trom an increased battery voltagewould be avoided. lt is believed that the arran ement shown in Fig. 5 inwhich the alarm c1rmit cuit is more sensitive to variations in voltage,

constitutes a more practical form of the mvention.

Fig. 6 shows the application of the invention to a mercury arc rectierhaving a cathode 20 and two anodes 21 and 22. vlhese anodes areconnected with the secondary 23 oi the transformer 24, the primar 25 ofwhich is connected with a source of a ternating potential. The mode ofconnection is that well known in the art for the purpose of obtainingConrectication of successive half waves. nected `between the anode 22and the cathode 20 is a relay 26, and similarly connected between theanode 21 and the cathode 20 is a re*- lay 27, which controls the alarmcircuit. Connected between the cathode 20 and the mid? point of thewinding 23 is the battery 28 in series with the sustaining coil 29.- Awork cirlcui-t 30 is shown connected across the battery 28. The mannerin which this circuit operates is .substantially that described inconnect1on with Fig. 1. If the device is rectifying llo properly, thevoltage between the anodes and the cathode will drop substantially tozero during the discharge of current therebetween. In the event thatlthe device is. notfunctioning properly, the voltage .between each anodeand its cathode will be maintained throughout the half cycles in whichrectification is supposed to take place, and accordingly there will beno margin of voltage to maintain operated the relays 26 and 27. Eitheror both of these will be released, and the alarm will be set inoperation.

While this invention has been disclosed as embodied in particular forms,it is to be'unf derstood that it is capable of embodiment in' other anddifferent forms without departing from the spirit and scope of theappended claims.

What is claimed is:

1. In a system for indicating the failure of a voltage rectifier torectify, the combination with a rectifier of asource of alternatingcurrent to be rectified connected thereto, a source of direct currentvoltage connected across the said rectifier and the said source ofalternating current in series, a differential relay, one winding 'ofwhich is connected across said source of direct current voltage and theother winding across the electrodes of the said rectifier responsive toa difference between the direct currentvoltage and the average of therectified alternating voltage plus the said-direct current voltage, and'an alarm signal controlled by the said differential relay.

2. In a system for indicating the failure 'of a voltage rectier torectify, the combination with a rectifier of a source of alternatingcurrent to be rectified connected thereto, a source of direct currentvoltage connected across the said .rectifier and the said lsource ofalternating current in series, a differenacross said source of directcurrent voltage and the other winding across the electrodes of the saidrectifier responsive to a difference between the direct current voltageand the. average of the rectified alternating voltage.

plus t e said direct current volta e, an alarm signal controlled by thesaid di erential relay, and a second relay to maintainr open the circuitof the alarm signal whenever the al ternating voltage is not beingsupplied to the rectifier.

3. In a voltage rectifyingvsystem', the combination withy a voltagerectifier of a source of direct current otential connected therewlth, asource o alternating potential connected with the said rectifier and thesaid source of direct current potential adapted-'to superimpose itsvoltage upon the said direct .current voltage, and a differential relayresponslve to the difference between the voltage of the direct currentvoltage 'andthe average of the rectified alternating voltage plus thesaid direct current voltage to control the operation of analarm signal.

^ 4'. In a system for indicating the failure of I lthe direct currentvoltage, a differential relay of which one windin is effectivelyconnected across the source o direct current volta e, and the otheracross the electro es of the said rectlfier, and an alarm signalcontrolled by the said differential relay to indicate failure of thedevice to .recti In testimony whereof, I have slgned myy 1st day of nameto this specification this October, 1925.

WILLIAM H. T. l HOLDEN. Y

